Normal Reference Ranges for Iron Levels in Blood
The normal reference range for plasma iron is 50-175 μg/dL (micrograms per deciliter), though laboratory-specific reference ranges should be used as the definitive standard due to methodological variations between testing facilities. 1
Key Iron Status Markers and Their Reference Ranges
Iron status is assessed using multiple parameters, as a single measurement rarely provides complete information about iron stores. The most important markers include:
Serum/Plasma Iron
- Reference range: 50-175 μg/dL 1
- Direct measurement of circulating iron
- Highly variable throughout the day
- Significantly affected by inflammation
Ferritin
- Reference ranges:
Transferrin Saturation
- Reference range: 20-50% 1
- Calculated as: (Serum iron / Transferrin) × 71.24
- Values <20% suggest iron deficiency
Total Iron Binding Capacity (TIBC)
- Reference range: 250-370 μg/dL (45-66 μmol/L) 1
- Reflects the capacity of transferrin to bind iron
- Increases in iron deficiency
Transferrin
- Reference range: 200-400 mg/dL 1
- Iron transport protein
- Levels increase proportionally to iron needs
Hemoglobin (for context)
- Men: 13.5-17.5 g/dL
- Women: 12.0-15.5 g/dL 1
Mean Cell Volume (MCV)
- Reference range: 80-100 fL 1
- Reduced in iron deficiency (microcytosis)
Important Considerations When Interpreting Iron Studies
Laboratory Variability: Due to methodological differences between laboratories, the reference ranges provided by the specific testing laboratory should always be used 1.
Influence of Inflammation: Most iron markers (especially ferritin) are affected by inflammation, which can mask true iron deficiency 1.
Ferritin as a Key Marker:
Diagnostic Accuracy: When multiple markers are abnormal, the diagnostic certainty increases. For example, low ferritin plus low transferrin saturation strongly suggests iron deficiency 1.
Gold Standard: When results are unclear, bone marrow iron staining remains the definitive test for diagnosing iron deficiency 1.
Clinical Implications
Iron deficiency is the most common nutritional deficiency worldwide, affecting approximately 2 billion people 2. Early detection through proper interpretation of iron studies can prevent progression to iron deficiency anemia, which affects approximately 10 million people in the US alone 2.
For patients with suspected iron deficiency, a comprehensive iron panel including ferritin, transferrin saturation, and serum iron provides the most accurate assessment of iron status, especially when inflammation may be present.
Remember that normal reference ranges may vary slightly between different laboratories and testing methods, so always refer to the specific ranges provided by your laboratory.